From b6ef91811f766f2c81ac19d4c3bf7ef002d8bccb Mon Sep 17 00:00:00 2001
From: Matthias Jaros <jarlucmat@mailbox.org>
Date: Mon, 9 Mar 2026 16:19:16 +0100
Subject: Further broke down structure and fixed bug that not all ports got
 scanned due to early executor shutdown. now handling everything nice in a
 future that gives return port if it is open

---
 .../com/it_jaros/networkScanner/ProgressBar.java   |  9 +++--
 .../java/com/it_jaros/networkScanner/Scanner.java  | 42 ++++++++++++++--------
 2 files changed, 31 insertions(+), 20 deletions(-)

(limited to 'src/main/java/com/it_jaros/networkScanner')

diff --git a/src/main/java/com/it_jaros/networkScanner/ProgressBar.java b/src/main/java/com/it_jaros/networkScanner/ProgressBar.java
index 044f683..2537d9f 100644
--- a/src/main/java/com/it_jaros/networkScanner/ProgressBar.java
+++ b/src/main/java/com/it_jaros/networkScanner/ProgressBar.java
@@ -14,10 +14,8 @@ public class ProgressBar {
     private ReentrantLock lock = new ReentrantLock();
 
     public void start() {
-        System.out.println("Progress:");
         this.hosts = new ArrayList<>();
-        // move cursor down depending on how many hosts have to be scanned
-        System.out.print("\n");
+        System.out.print("Scanning targets...\n\n");
         ui.scheduleAtFixedRate(() -> {
             lock.lock();
             drawProgress(false);
@@ -31,9 +29,10 @@ public class ProgressBar {
             drawBar(progress);
         }
 
-        // move cursor up again
-        if (!last)
+        if (!last) {
+            // move cursor up again
             System.out.print("\u001b[" + hosts.size() + "A");
+        }
     }
 
     public void submit(Progress progress) {
diff --git a/src/main/java/com/it_jaros/networkScanner/Scanner.java b/src/main/java/com/it_jaros/networkScanner/Scanner.java
index 1bc8848..f5205d5 100644
--- a/src/main/java/com/it_jaros/networkScanner/Scanner.java
+++ b/src/main/java/com/it_jaros/networkScanner/Scanner.java
@@ -43,9 +43,7 @@ public class Scanner {
         try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor();) {
             List<Future<ScanResult>> futures = new ArrayList<>();
             for (String target : targets) {
-                futures.add(executor.submit(() -> {
-                    return scanTarget(target, ports);
-                }));
+                futures.add(executor.submit(() -> scanTarget(target, ports)));
             }
 
             futures.forEach((f) -> {
@@ -64,32 +62,46 @@ public class Scanner {
 
     private ScanResult scanTarget(String target, String ports) {
         PortRange portRange = new PortRange(ports);
-        AtomicLong scanSlotFactory = new AtomicLong(System.nanoTime());
+        AtomicLong portSlotFactory = new AtomicLong(System.nanoTime());
         Queue<Integer> openPorts = new ConcurrentLinkedQueue<>();
 
         Progress progress = new Progress(target, portRange.getTotal(), new AtomicInteger(), new AtomicInteger());
         progressBar.submit(progress);
 
         try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor();) {
+            List<Future<Integer>> futures = new ArrayList<>();
             while (portRange.hasNext()) {
                 final int currentPort = portRange.next();
-                executor.submit(() -> {
-                    try {
-                        waitForSlot(scanSlotFactory);
-                        if (isTargetPortOpen(target, currentPort)) {
-                            openPorts.add(currentPort);
-                            progress.open().incrementAndGet();
-                        }
-                    } finally {
-                        progress.done().incrementAndGet();
-                    }
-                });
+                futures.add(executor.submit(() -> scanPort(target, portSlotFactory, currentPort)));
             }
+
+            futures.forEach(f -> {
+                try {
+                    int port = f.get();
+                    if (port != -1) {
+                        openPorts.add(port);
+                        progress.open().incrementAndGet();
+                    }
+                } catch (InterruptedException | ExecutionException e) {
+                    e.printStackTrace();
+                } finally {
+                    progress.done().incrementAndGet();
+                }
+            });
         }
 
         return new ScanResult(target, openPorts);
     }
 
+    private int scanPort(String target, AtomicLong scanSlotFactory, final int currentPort) {
+        waitForSlot(scanSlotFactory);
+        if (isTargetPortOpen(target, currentPort)) {
+            return currentPort;
+        }
+
+        return -1;
+    }
+
     private void waitForSlot(AtomicLong scanSlotFactory) {
         if (delayInNanos > 0) {
             long slot = scanSlotFactory.getAndAdd(delayInNanos);
-- 
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